David wrote:
[...]
If you are interested in a wind vane self steering just a simple horizontal axis vane direct to the tiller would probably work for a boat the size of your. In his book 'Wind-Vane Self Steering' Bill Belcher presents plans for a simple horizontal axis wind vane built fairly easily from plywood. If you are interested in building one of these I have the book and am happy to scan the plans and building instructions and email them through to you. It does require quite a large vane to generate enough power, but these simple vanes have been used successfully on many small yachts.
David,
Thank you for sharing the drawings. After studying them for a bit I remembered that Arne had built a wind vane, named Otto, mostly following the OGT MKII plans.
Between the photos in Arne's write up and the drawings you provided I think I might be able to build a vane like this. I may not be terribly good at it, but I am comfortable working with plywood and epoxy. I may even be able to build this for less than the cost of a Simrad TP10.
Near the end of his Otto summary, Arne wrote, "I would not suggest the same setup on a boat which is directionally unstable (or only just stable)."
My boat (mostly) balances well on the wind, but on a run there is significant weather helm since the sail is almost entirely on one side on the boat. On flat water and consistent wind speed I can (mostly) correct for this by having the tiller off to one side.
When I was out in some waves, and running down wind, the 'feel' on the tiller was changing constantly. As each wave passed under me the tiller would need more and more input to steer the boat until the wave was mostly passed at which point the tiller again became effortless to move.
So ... is my boat directionally stable enough to hold a course using the OGT MKII attached directly to the rudder?